Flikr Cool Data Visualization group
Flikr--Innovation in visual design group
Flikr Diagrams group
Flikr Infographics group
Flikr flowing Data group

Very Basic graph and chart tools:

GoGo Plots--a very basic program that's useful for making plot charts
ChartGo--simple program for making a variety of bar graphs and pie charts
HohliCharts--simple graphs, pie charts, and venn diagrams
ChartGizmo--simple graphs, pie charts, bar graphs
PieColor--A tool specifically for making colorful pie charts
ChartTool--another one

Slightly more complicated chart tools:

ChartsBin--Still in beta, so free for now (Feb, 2011). Lots of chart forms and templates. Has more options than the group of tools above.
DataMasher--A great site for working with government data. Has lots of data from government sources and allows you to combine it and present it in a variety of ways
Cynergy Systems--in some ways similar to DataMasher, but this site works with info from the US Census Bureau
Visual Economics--charts and tools that are useful for presenting data about business and economics
ManyEyes--allows you to build a wide variety of chart types using your own data or using tons of data that has already been loaded onto this site

For Flow Charts:

SlickPlan--for creating simple flow charts
LucidCharts--a similar flow chart program but with a lot more options and tools

Great models (and tools) for data visualization

Data visualizations (and tools) for US Government data

Better World Flux--a data tool that lets you work with information from the United Nations (same data that Hans Rosling uses)

Cool Data blog
Visual Complexity blog--
Neoformix--a blog devoted to using visualization to make sense of data
Information Aesthetics--another great blog of this nature
50 Great Examples of Data Visualization
Data Mining--a blog about gathering data
20 Data Visualization Blogs __--some really great suggestions here__

Info on using Flikr for Data Visualization

GapMinder Home page--Hans Rosling's work
Doing your own Gapminder charts:
Tutorial for Google motion charts
Google's own tutorial
When to use a motion (trend) chart v. when to use a standard graph
Tutorial (including some video) from the Cool Data blog
GapMinder v. Motion charts

More...

3 new info-gram platforms (2012)

Places to Find Data

DataMarket--a huge search engine that helps you gain access to all kinds of data-over-time. This should be one of the first places you check.
List of 30 great sources for finding data; make sure to read the further suggestions at the bottom of the page.
Research Pipeline--a blog that has information about available data sources1
NationMaster--a place to find data about different countries and comparisons of these countries
The Data Store--based in England, but tons of data from everywhere
TimeTric--data on economic issues
InfoChimps--more data from everywhere
Data.gov--Government site with lots and lots and lots of data
GapMinder--GapMinder provides lots of data that you can export and use on your own

Google Public Data Explorer--a new (2/2011) project from Google. Provides you with a variety of rich data sets and gapminder-like tools to explore this data.